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The health impact of coal and bagasse ash on people living near pow...

Chapter 3


3.0 Method.

For the present study two tools were identified and seem to be appropriate in investing the health impact of coal and bagasse ash on the people living near facilities. They are

Health Risk Assessment (HRA) and

The WHO Health Impact Assessment tool.

3.1 Health Risk Assessment (HRA)

Everyday people are exposed to chemicals, depending on certain criteria chemicals can be either beneficial or dangerous depot human health. Some chemicals may be essential for the maintenance of a good health at low levels whereas others at low and high levels pose problems to the human health. HRA are employed to establish whether a specific chemical represent a momentous risk to human health (California Environmental Protection Agency ,2001). There are several question that are raised in the HRA.

3.1.1 Hazard identification

The first step in health risk assessment is hazard identification. The types of health problem that are associated with a chemical assessed by reviewing published studies of its effect on humans and animals (CEPA, 2001). In order to know what are the hazards present in coal and bagasse ash. The chemical’s composition and concentration present in coal and bagasse ash must be known. The composition and concentration of bagasse ash is addressed in section xxxxx and section xxxx. A significant step in hazard identification is the assortment of key study that are capable of providing accurate and reliable information on the identified hazard. The end point of this step is showing that human may or may not be at risk. The threshold of exposure to a chemical either long or short term, its probable effect or its toxicity are factors that are taken in consideration when hazards are identified.

3.1.2 Exposure assessment

Exposure to hazard is assessed to relate the exposure and the onset of a health effect. Most scientist think that exposure is directly proportional to the onset of disease. People are usually exposure through the three main routes of entry of chemical to the body. These are inhalation by breathing, ingestion through eating and absorption by the skin. The pattern of duration and intensity of exposure are used to identify which hazards are more significant to the person or population. Way in which scientists examine the exposure are mainly through air, food, water and soil monitoring. Computer modelling is also used to assess exposure (CEPA, 2001).

3.1.3 Dose-response assessment.

During the dose-response assessment phase the information collected during the hazard identification step are used to approximate the amount of chemical which has the potential to result in a particular health effect in humans. A well known principle in toxicology is that “the dose makes the poison.” An example is sugar which is harmless in small quantities, but it can cause illness in large dose. Researchers carry out dose response assessment to estimates how different levels of exposure to a chemical impact on the severity and likelihood of health effects. Chemicals that cause cancer have different dose-response relationship as compared to those that causes other health problems (CEPA, 2001). Cancer Effects

Chemicals that causes cancers are unlike to other chemicals, even a low exposure can cause a cancer many years after the exposure. The general assumption used in risk assessment is that there are no exposures which are zero risk potential except if there is clear evidence otherwise. A chemical will cause cancer if it happens to alter the cellular processes in a way that causes cancer. So low concentration of carcinogens might increase the risk of cancers consequently it is difficult to estimate the risk of cancer because cancer is a progressive disease which goes through cellular transformation before developing into a cancer. The best accessible information of a chemical’s potential of causing cancer derives from studies which laboratory animal are exposed to levels of chemicals that are above human background exposure. Researchers usually make use of mathematical models to estimate the probability of a chemicals potential of causing cancer. Data from new studies are used to update and improve the risk of cancers (CEPA, 2001). Non cancer Effects

Chemicals with noncancerous effect such as nervous system disorders, asthma, birth defects and developmental problems in children become more severe as exposure to a chemical increase. Health determinants help in screening which population is more affected by varying levels of Chemicals (CEPA, 2001).

3.1.4 Risk Characterisation

The final step in health risk assessment is risk characterisation. It has for aim to bring together all the information gathered in the previous three steps to calculate the risk of health effects in an exposed population. The information builds up from the exposure and dose response assessment are analysed to formulate the expected risk that are expected to occur within an exposed population. The risk is characterised into cancer and non cancer health effects (CEPA, 2001).

3.2 Health impact assessment

Part of the who guidance for the HIA studies

The WHO guidance for HIA studies was used as an assistance for investigating the health impact of coal and bagasse ash. The general aspects that should be taken into consideration according to the WHO guidance are:

Which group are affected and in what way?

Is the effect reversible or irreversible?

Does the effect occur on the short or long term?

Is the effect permanent or temporary?

Is it of local, regional, national or international importance?

Is it beneficial, neutral, or adverse?

Are health standards or environmental objectives threatened?

Are mitigating measures available and is it reasonable to require these?

Are the impacts direct, indirect and or cumulative?

3.2.1 The HIA process:

According to the NHS Health Development Agency (2002) The HIA process entails the collection of a wide range of proof in order to understand and interpret health risks and potential health gains. The method of undertaking the HIA is not a fixed one nevertheless there is a wide agreement about the core stages that should form part.

The core stages include:

Screening-decide whether an HIA is the best way of ensuring that the health concerns are addressed effectively.

Scoping- decide the way the HIA should be carried out.

Appraisal of evidence- identifies and considers the evidence for potential impacts on health.

Development of recommendations- provide policy maker a thoughtful understanding of the key health impacts, means of encouraging positive impacts and decreasing negative impacts.

Monitoring and evaluation- the impact must be monitored and evaluated to understand if the implementation has bring about changes as predicted. Evaluation helps in identifying the loopholes of the HIA and considers whether the HIA could be done more effectively

3.2 Literature review

A literature review was done to gather maximum evidence from published documents. These published documents are of vital importance since the study which is being carried is a non epidemiological one. Evidence of the impact of particulate matter will give more power to the current study as the equipment used for the quantification of these impact are very expensive and a colossal budget is also needed to carry such study.

Categories of Studies which were of interest to the literature review are:

Broad study on effects of coal and bagasse ash

The reuse of coal and bagasse ash

The hazards associated with bagasse and coal ash

Health Impact of metals and metalloids present in coal and bagasse ash

3.3 The data collection procedures

The collection of primary data was done by interviewing people living near power plant facilities in order to screen for potentials health problems. The questionnaire was design in such a way to cover a number of aspects that are raised in the WHO guidelines for HIA.


One hundred people (61 male, 49 female) participate in the survey which was made at L’escalier a small village in the south of Mauritius. L’escalier was chosen to carry out the study because at l’escalier resides a power plant which is involved in the production of electricity from coal and bagasse (the complete village and company profile are captured in the appendix). People walking on the road were selected at random to participate in the survey. The participants were mainly people living in the region of l’escalier. Some people were not willing to participate others were at ease and were disposed to participate. The great majority of participant answered the question very rapidly. People fail to answer question 12 and 13 saying that it was a bit personal. I notice a delay before they answer question 12 and 13 specially the male respondents this delay show that they were not sincere in their answer. So question 12 and 13 will not be used in the analysis.


The interviewer used a questionnaire to interview the respondent. The interview was done in Creole to increase the interaction between the interviewer and the interview. The questionnaire consists of 18 questions which include one close ended question.


People walking on the road were selected at random to participate in the survey. Some were interviewed in group for example people on the bus stop were interviewed in group and the interview was done quickly because at any time the bus can come and interrupt the interview.

The first step of the interview was to introduce the subject to the participant. the scope of the interview were introduced to them and they were asked to answers as more precisely as they can.

When the interview was over the data was compiled and The SPSS software was used to compute and summarise the data collected from the interview.

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